As to the 3 seconds, that's normal but I'll skip writing why.
I can't know what you have installed other than Windows but you can do without Avast for a test run. We want to head to stock and let Windows Defender and detaults work next.
I've been having issues with my internet lately. Sites such as YouTube and Facebook work completely fine, but most only work for a few seconds/minutes. When going on another site I get the error 'ERR_CONNECTION_TIMED_OUT' but after waiting a bit they work again only to lose connection once more after another period of time. This occurs in all my browsers(Microsoft Edge, Mozilla & Chrome). I tried booting my pc in safe mode & after like 3 seconds of seeing the error again all sites work fine without losing connection like in normal mode. I could even play online games without losing connection (although no sound & massive fps drop). Malwarebytes & Avast didn't find anything viral but at this point I think there has to be some service or program blocking the access to those sites periodically.